Many overweight individuals attribute their weight management problems to dysphoric mood combined with an irresistible urge to eat carbohydrate-rich snacks. They also report mood elevation following the consumption of foods rich in carbohydrates. This proposal is designed to investigate whether the phenomenon of carbohydrate craving can be objectively demonstrated and whether carbohydrate self-administration serves to self-medicate unwanted negative moods. A reason why one might self-administer carbohydrates to improve mood is that selective intake of carbohydrate-rich protein-poor foods elevates the ratio of tryptophan to large neutral amino acids (LNAA), which, in turn, increases brain tryptophan influx and serotonin synthesis. Increased serotonin levels in the brain are believed to alleviate dysphoric mood and appetitive dysfunction in individuals with major depression, eating disorders, and obesity. Similarly, eating carbohydrates may improve mood in dysphoric carbohydrate-cravers who overeat carbohydrates. However, mood changes that appear to be nutrient-induced could arise if food-related expectations influence behavior in a way that creates a self-fulfilling prophesy. The purpose of this study is to determine whether the effects of carbohydrates on mood and cognition that are reported by carbohydrate-cravers persist in a double-blind controlled study. It is predicted that the "carbohydrate-craver" will experience an improvement in both mood and cognition following ingestion of a carbohydrate-rich beverage versus a taste-matched protein-rich beverage, even when expectations are controlled by blinding subjects to the macronutrient content of the beverage. It is predicted that when given a choice between the two beverages, the subject will choose the carbohydrate-rich beverage and that mood elevation will be greatest when carbohydrate is chosen and administered by the subject rather than by the experimenter. Mood is not expected to parallel blood glucose changes, excluding an explanatory mechanism based on hypo- or hyperglycemia. Results of this study will provide further insight into mechanisms that elevate carbohydrate-craving and consumption of carbohydrates and enhance our general understanding of how eating affects psychological well-being. This study may have implications for the treatment of eating disorders and depressive syndromes that are characterized by carbohydrate craving and over-consumption.